Apple II

Apple II (Not Plus) Board has Issues

Recently got a Rev.2 Apple II board.  Originally had AppleSoft ROMs, But the AutoStart had a bad pin (broke off) so I replaced them with an Integer set I had on a II+ board.  The board boots to the Machine Monitor, and with a ROM switch card (AppleSoft onboard) in Slot 0, it will go to BASIC.  I connected a Disk II in Slot 6, and put in a copy of Apple-cillin II.  It loaded fine, so I tried a copy of DOS 3.3, and it either hangs after splash screen or crashes.

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MMU problem?

Hi all,

 

I found a IIe in the loft (PAL version) and it does not boot.  Clock phases are correct and address/data lines look OK.  Adr downstream of buffers 74LS244 also look OK and buffers test OK (in an LED & switch tester!). There is no beep.

 

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Apple /// ROM Adapter and Custom ROM Project

I wanted a reliable and easy to use adapter for the Apple /// system ROM ("B9 ROM"). Something to plug standard EPROMs & EEPROMs. I want to make a few ROM extensions - making use of the second ROM bank, which was orignally unused. Apple only installed 4KB ROMs, though 8KB were supported (split into two banks) - but the unused second bank just returned random data. Maybe Apple intended this to be used for future updates. But we all know that never happened...

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Anyone repaired a joystick with broken pins?

Unfortunately I have three TG Products joysticks with one or more broken pins.  Two have ribbon cables and one has the round insulated cable.

 

Has anyone succsessfully repaired this and if so how have you done it?  Thanks for any info!

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AdvSkel65 progress report but bug still there

Hi!  I just replaced the version of printtok used with AdvSkel65's no hidden memory C64 port with a newer version of printtok, disabled some at-first-unneeded code and bought .11k.  I need to continue upgrading AdvSkel65 now.  But the bug is still there.  :(  BTW, I am using an old version with Smir 3, 1.  It's going to take a lot of effort to upgrade Smir 3, 1, as the whole mechanism with handling tokens changed.  :(  Now, tokens are in the range 0x80-0xFF, while in older versions, some tokens start with a '%' and are followed by a letter or a number.  I'm using Notepad++ on a Win11/64 lap

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AdvSkel65 doesn't work on 128k Apple2enh

Hi!  I've been heavily optimizing and improving my AdvSkel65 program.  Right now, I'm preparing the latest version of PrintTok for my codes, and this version supports up to 128 one-byte tokens and more text adventure-related control characters, including tab and clear screen.  However, the 128k Apple2enh version gives me an error #67 while loading a stub into memory.  The 64k version shows no problem, and neither do the other ports.  I suspect stack corruption, as that happened to me several times before.  I attached the ProDOSi code to open files and read data and the code's main file.  If

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Custom Enclosure - Floppy Emu - Source Files

PTB has released all source files for his Floppy Emu ][ under the Creative Commons Attribution- ShareAlike license.

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MII: New IIe open source emulator, mine this time!

Monochrome Double-Hi res

This has to be the worst case of feature creep in history, I wanted to hack an emulator for one specific project (Testing a Dan ][ card tool!) and couldn't find something I liked enough -- so, I wrote my own! So here it is, MIT licence. Tons of stuff work, a few bits needs work, but it's perfectly usable as is already!

Funny thing is, I haven't even started writing the Dan][ tool I wanted, but I no longer have an excuse now -- procastination at it's best!

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Apple II Power Supply rapid clicking

Hi All,

I'm stumped with this power supply.  Hopefully someone can help me out.

 

Symptoms

When I power it on underload, it makes a 6khz buzzing sound.  It sounds similar to the noise made when you plug in a working power supply without a load, but the click is 10x~20x faster.  Here is the waveform that is generated when plugged in under load:

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Putting a PT-65B switchmode power module into an Apple IIe

You might ask why I did not attempt to repair the original power supply (only the usual culprit, the "Rifa" capacitor had exploded / cracked open). The reason, other than the 220V issue which limits the Apple IIe to my lab, where I have a step-up transformer, is that all the electrolytic capacitors in the original power supply are 40 years old, and beyond their safe life span. Which means they all need to be replaced to have a reliable power supply which would not cause more trouble down the road. And unlike some people believe, it is neither trivial nor cheap to replace the electrolytics in a switchmode power supply. They need to be chosen carefully to be suitable for this application, and "normal" electrolytics designed for filter purposes after an AC rectifier just won't do. These are specified for 120 Hz operation only, while the typical switchmode power supply works at more than 100 x that frequency. For electrolytics in switchmode power supplies, ESR at high frequencies (up to 100 kHz or more) and ripple current ratings at higher frequencies are critical, otherwise, they might just overheat and explode. So be warned, don't attempt to replace electrolytic capacitors in switchmode power supplies unless you are competent in this field of engineering. Now, the bad news is that suitable electrolytics are special types which are so expensive that replacing all of them would cost more than a brand new PT-65B. Besides the mechanical issue that none of the modern replacements have the same footprint anymore. Even electrolytics did shrink in size in the past 40 years. This mechanical complication is worse than you might think - the issue is how to bend the leads properly without damaging the seal of the rubber plug. It can be done, but then the next issue is how to prevent them from wobbling around, they need to be glued together somehow. Same reason why "Mean Well" puts white silicon goop in their power supplies to secure larger components, like electrolytics, in place. All this conspires against replacing these old electrolytics in the old power supply PCB. IMHO, it's simply not worth the time, money, and effort.

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